Tooth tales told by dental diet proxies: an alpine community of sympatric ruminants as a model to decipher the ecology of fossil fauna

International audiencePaleobiologists tend to use dietary information as an ecological indicator because diet is a fundamental link between an organism and its environment. However, the ecological information from fossilized hard tissues is often difficult to interpret, because links between environment, diet, and hard tissue biology are insufficiently studied in modern communities.To address this dilemma, we investigated dietary proxies commonly used by paleobiologists in a 4-ruminant community from the French Alps. Dental microwear textural analyses are applied to 82 specimens of roe deer, red deer, chamois, and mouflons. Intra-tooth serial enamel stable carbon and oxygen isotope analyses of the structurally bound carbonate were applied on eleven specimens, with isotope-based niche reconstructions, and inverse modeling of original seasonally variable oxygen isotope inputs.While microwear complexity largely overlaps, both inter-individual dispersion and heterogeneity of complexity together with the anisotropy track dietary differences. The red deer is likely more engaged in grazing than the two bovids, which both plot as mixed feeders. When combined, dental microwear and carbon stable isotope analyses accurately reflect known ecological separation between the chamois and the roe deer. Both stable isotopes suggest niche separation by increasing enrichment from roe deer to red deer, to chamois; mouflons appear to feed as generalists. In roe deer, which shows the highest enamel oxygen isotope range (5.7 ‰), variation is nevertheless constrained compared to oxygen isotope ranges observed in regional precipitation, where the mean annual range reaches 9.9 ‰. However, through inverse modeling we estimate seasonal input ranges that average 9.7 ‰, a result strikingly similar to regional values. Altogether, our data demonstrate that given appropriate sampling strategies and modeling approaches, microwear and isotopic data can be effective tools for demonstrating niche separation among multiple sympatric herbivorous taxa